LAGOS, June 13 (Reuters) - Nigerian billionaire AlikoDangote is aiming for a valuation of up to $40 billion for hiscement company at its London listing next year, several timesthat of top global rival Lafarge.

Africa's richest man told Reuters in an interview in Lagosthat funds from the offer of 20 percent of the shares in thecompany were not needed for its rapid expansion, but would beused to pay off investors, including himself.

Dangote's cement empire stretches from Senegal to SouthAfrica, benefiting from a construction boom across one of theworld's fastest growing continents.

In a difficult global environment for share offerings,Dangote said he was not discouraged by the tumble in Facebook's shares since they listed last month.

"Where the assets of Facebook were hype, we have realassets," said Dangote, setting out the market capitalisation heexpected for his firm at the listing planned for late next year.

"It depends on the market, but it should be something like$35 to $40 billion dollars. We are targeting something likethat," said Dangote, 76th on the Forbes list of the world'sbillionaires and its fastest riser in 2011.

He said his main aim of the London share offer was tostrengthen corporate governance.

If he raises as much as he hopes, it would value Dangotecement at much more than rival Lafarge, which has amarket capitalisation of around 9 billion euros ($11 billion).

Dangote Cement, Nigeria's biggest listedcompany, currently has roughly the same market value as Lafarge.

Dangote Cement trades at 9.3 times forward earnings whereasLafarge trades at 11.4, according to Reuters data. But Lafarge'srevenues were more than 13 times as high as Dangote's last year.

Dangote said his rapid expansion would make his companyconsiderably larger than it is now by the time of the listing -with new plants due to be completed in 13 other Africancountries by then.

Lafarge, meanwhile, is in the midst of a cost-cuttingprogramme in an effort to offset the impact of stagnation in itsmain markets and to cut its debt.

Dangote said he had raised his production target to 60million tonnes a year by 2015 from around 28 million tonnes atthe moment.

Dangote commissioned an expansion of his Obajana cementplant in central Nigeria on Monday to raise capacity to 10.25million tonnes a year, making it one of the world's largest.

The speed of the company's expansion across Africa hasraised alarm bells amongst some analysts, but Dangote said hehad no concerns at burning through cash too quickly.

"Cash flow is excellent, so the cement business does notreally need to raise funds," he said in his office in a Lagosbusiness district, adorned with a giant photo of the Obajanafactory and a large map of Africa.

He said the company's lack of debt would be a big advantageif conditions turned harsher. ($1 = 162.5500 naira) ($1 = 0.7953 euros)